The Ultimate Rivalry
by Raptorguy19
Summary: Several years after the Disasteroid incident, Dark Danny returns with one goal in mind: revenge. A new enemy also threatens to destroy the world, and Danny Phantom alone is not powerful enough to stop them. Join Danny and Team Phantom as they pick up their ecto-weapons once again in a dramatic fight for control - before they run out of time.
1. Prologue

**WALKER'S PRISON**

Walker patrolled the hallways of his prison, overseeing the day-to-day care (if you could call it that) of the prisoners. He was especially wary of one particular prisoner. This prisoner had been locked up for millennia but was a very powerful ghost. Since he had been locked up for so long most had forgotten about him, but Walker knew that he was probably the most powerful prisoner of them all. He always worried that because this ghost had very...particular powers, and he only used these particular powers when the time was right, that he would be able to escape with ease. Walker always prided himself in maintaining a tough prison with tough guards but he had to be especially careful around Kairos.

He was, after all, the younger brother of Clockwork.

In fact, Clockwork himself was the one responsible for turning his brother in. Clockwork was the ultimate master of time, with the ability to see the past, present, and future; the ability to warp and bend time; as well as other abilities. His young brother had the same abilities but with less of a grasp on them and a youthful arrogance. Kairos was also reckless, but he was very cold and calculating. He only took action when the timing was right.

Kairos hadn't done any serious damage to humanity or ghost-manity _yet_. He had been locked up mostly as a precaution, to prevent him from causing any harm. Because of his relative lack of experience with manipulating time, he could only use his powers if he had a time staff.

Or so Walker thought.

Walker reached Kairos's cell and the two had a stare-down, just like they always did. Unlike his brother, who always wore a robe and was constantly going from young to old and back again, Kairos chose to maintain his age. He wore dark black pants and had an hourglass symbol on his bare chest. His wings were tucked up against his back; since he had no need for them in the cell, he often kept them tucked in because it was more comfortable that way. Kairos gave a smirk and a wink, as he always did, and Walker narrowed his eyes. After fifteen seconds, Walker scoffed and started to walk away.

"Yoo hoo, Walker!" Walker's eyes immediately went wide at the sound of Kairos's voice. He hadn't heard that voice since he first locked him up all those millennia ago. Walker stopped dead in his tracks and spun around to find Kairos standing directly behind him. But how could that be? The cells were impenetrable by ghosts; only humans could have passed through the bars. Walker was again taken aback when he noticed Kairos was twirling his jail keys on his index finger.

Walker quickly regained his composure. "You're done for, punk!" he sneered. He snapped his fingers and instantly Kairos was surrounded on both sides by members of the Ghost Zone Police Department. Immediately they rushed at the prisoner.

Just before they reached him, Kairos said, "Ah buh buh, time out!" To Walker's surprise, the inexperienced time lord snapped his fingers and was able to freeze everyone dead in their tracks. With a smug grin on his face, Kairos spread his wings, dropped Walker's keys, and floated safely away. ONce he was a safe distance away he said, "Time in" and snapped his fingers again. The guards collided and very briefly fought each other before realizing that Kairos was long gone.

An alarm sounded throughout the prison. More guards were dispatched and began frantically searching for the escaped convict. Soon, Kairos was found in a hallway near the exit to the prison. Kairos turned to face the large gathering of guards and smirked an evil smirk. "Time out," he said, snapping his fingers again. The guards froze, but almost instantly unfroze. "Ugh, darn it! These powers still don't work right without a time staff. No matter..." Kairos folded his wings around his body and disappeared, leaving a clock symbol behind briefly.

Kairos took one last look back at the prison and chuckled to himself. He began to float away from the prison before he ran smack dab into his brother.

"Little brother," Clockwork said. Though he rarely expressed emotion in his words, they carried a harsh undertone.

"Hmph, Clockwork," Kairos hissed. "Right on time."

"We both know how this is going to end, Kairos," Clockwork said. "You may have been able to escape a few jail guards, but there's no escaping the Master of Time." With those words, Clockwork transported both of them to his tower.


	2. Chapter 1

**CLOCKWORK'S LAIR**

Kairos and Clockwork stood face-to-face in Clockwork's time tower. They glared at each other for what seemed like an eternity. Both of them knew what was about to transpire, but it was all in due time.

Kairos broke the silence and said, "Now, now, big brother, don't be unreasonable. We both know how this is going to play out."

"No, _I_ know how this is going to play out," Clockwork responded. " _You_ only see what you want to see. You're just like the Observants, observing one time line at a time instead of seeing the whole picture."

"You have the same powers I do. What makes you think you're better than me? What makes you think you can see more than I can see?"

"Stop playing games, Kairos. We both know why you're here. You came for _him_."

"It is my destiny to unleash chaos upon the world and the time has come. But I cannot do it alone. You know this, big brother. That's why I need him, see."

"You know nothing about your destiny, only your selfish desires," Clockwork said emotionlessly. "And you know as well as I do that I have been tasked with guarding him." Clockwork created several powerful clones of himself. "And you know as well as I do that I cannot allow you to have him," he and his clones said simultaneously. Kairos frantically dodged each attack thrown at him until it became too much. Soon he was getting tossed around like a rag doll by Clockwork's clones. After several minutes of this, he collapsed to the ground and held his hand up in defeat.

"I get it, big brother, I get it."

"No, you don't get it. You never will until you clear that head of yours of your arrogance. Time keeping takes patience, neutrality, and a clear head. One day you will be by my side, and you will see that you are wrong."

"Teach me, brother. Teach me how to be more like you."

Just then, Clockwork got an idea. "Fine," he said. "Since you seem so eager to learn..."

Kairos smiled. Both he and Clockwork knew this moment was coming. Clockwork grabbed a dusty thermos from a shelf, which was slightly dented. "I'll just have to teach you." He sighed and opened the thermos, unleashing what was inside. From out of the thermos emerged a whirlwind of energy, and from that whirlwind of energy manifested one of the most dangerous spirits to exist in any timeline. The dark version of Danny Phantom.

Immediately, Clockwork froze Dark Danny so that he couldn't take any action against him or his brother. Despite being a cold and calculating villain, Dark Danny had a confused look on his face, but this look of confusion was quickly replaced with a cold smile when he saw Clockwork.

"Ah, Clockwork. You must be meddling _yet again_. What's your objective this time?"

" _My_ objective is to set you free," he responded.

"I'm not in the mood for games. Why did you set me free?" Dark Danny demanded.

Clockwork instantly disappeared and Kairos took his place. "Hello, Daniel," Kairos said. "The time has come for you to unleash chaos upon the world."

"Unleashing chaos sounds like a blast...literally," Dark Danny responded. "Who are you?"

"I am Kairos, manipulator of time and younger brother to Clockwork," he responded.

Dark Danny raised a suspicious eyebrow. This could very well be another one of Clockwork's cleverly disguised plots. Setting him free could be the gateway to wiping him out once and for all. But there was no way he could have escaped the thermos, so what would be the point in that if he was locked up for all eternity anyway? He had a natural distrust in Clockwork, but he couldn't discount the fact that he was a free ghost now.

Kairos reversed the time freeze on Dark Danny and he landed on his two feet. Kairos grabbed a time staff that was hanging on the wall and said, "Come, we have much to do."

"Yes," Dark Danny responded, grabbing a time medallion hanging from the wall and pocketing it. "I know the perfect place where we can start. _Amity Park, here comes your worst nightmare_ , Dark Danny thought to himself.

 **FENTON WORKS**

"Happy birthday!" everyone cheered. Danny Fenton leaned over the table and blew out the eighteen candles on his cake. Finally, he was an adult! That meant he was in his last year of Casper High, then he could move on to college and focus on his dream of becoming an astronaut. Danny simled and looked at his friends and family. His parents sat across from him, beaming with pride at their half-ghost son who had become a man. Jazz, on his right, had flown out from California (where she was attending Stanford University) to be with Danny on his special day. Unfortunately, Mayor Tucker couldn't be there but they made arrangements to attend a Rage Against The Machine concert later that day. Finally, Danny's girlfriend, Sam Manson, was on his left side, and his little "cousin", Dani, sat with Jack and Maddie.

"Thanks guys! This is awesome!" Danny said. He looked at the cake again, which was shaped like an astronaut with "Happy birthday!" written across the chest.

"Anything for our favorite half ghost, Danny. Congratulations on becoming a man," Jack responded with a smile.

Danny chuckled. "Thanks, dad, but it's not like this is a huge accomplishment. All I did was turn a day older than I was yesterday."

It had been several years since the Disasteroid had nearly destroyed Earth. The Fenton ghost portal had been permanently closed and destroyed right after the incident, and with no regular access to the human world, very few ghosts had come to Amity Park since then. When the occasional portal did open up, nobody came through. With Danny's newfound reputation as a half-ghost crime fighter and the ghost who had saved both the human world and the Ghost Zone, most ghosts now left him alone out of both fear and respect.

He was also treated as a celebrity in the human world. He went from being one of the least popular guys at Casper High to being on top of the A-listers in an instant. But he didn't want to be on top of the A-listers, he was satisfied with the life he had been living before. Though he appreciated the attention right at first, it eventually became excessive when everyone wanted to talk to the Ghost Boy. Newspapers, classmates, even his teachers wanted to know more about him and constantly hounded him with questions. Eventually it let up, but he still had to be wary of the occasional swarm of paparazzi.

With no ghosts to fight, Danny had become an honorary member of the Amity Park Police Department. He was only called in the biggest of emergencies, but having superpowers substantially helped him fight crime and rescue people from dire situations. In fact, crime was at an all-time low in Amity Park. Just yesterday he had saved over fifty people being held up at gunpoint at the local mall. Today being his birthday, he had decided to take the day off and spend it with his family and friends.

"Look at you. You're a man, you're a crime fighting ghost, and you're romantically involved with your best friend." Jack shed a tear. "I could well up with pride, son."

"Please don't," Danny said, wincing.

"We're all proud of the man you've become, little brother," Jazz said.

"Yeah, Danny," Sam chimed in. "We've all been through a lot together. And now you're closer than ever to achieving your dreams."

Danny smiled and kissed sam. "Thanks, Sam."

"Time to cut the cake, sweetie," Maddie said. She handed Danny a knife and asked, "Will you do the honors?"

"Of course," Danny said, taking the knife. Before he could start cutting, his ghost sense went off. This confused Danny, as he had not seen a single ghost (besides himself) for years. He dropped the knife.

Dani also sensed the ghost. "Danny, did we just..."

"I just...sensed a ghost," Danny said. He narrowed his eyes and looked around but didn't see anything. "Whoever you are..."

"I AM THE BOX GHOST!" a voice yelled from the box the cake had come from. "AND I HAVE RETURNED TO SEEK VENGEANCE ON MY GREATEST FOE!" The Box Ghost rose from the cake box and flung it at Danny. Without blinking or expressing any emotion, Danny went intangible and the box passed harmlessly through his body.

"Really?" Danny asked. "Could you take a hint already and just leave me alone?"

"Don't worry, Danny, I'll take care of this one," another voice said. _This_ voice scared Danny and Sam. They knew this voice all too well. But how could it be? Before any of them could respond, a beam of red ectoplasmic energy sent the Box Ghost hurdling backwards and through the wall of the kitchen. Once the Box Ghost had been dispatched, Dark Danny made himself visible.

Danny immediately jumped up and yelled, "I'm going ghost!" He transformed into his ghost form and rose up to meet his alternate future self.

Dark Danny noticed that Danny had gone ghost in front of his family. "Ah, so they know now," he said.

Maddie and Jack both produced plasma pistols and aimed them at Dark Danny. "Who are you and what do you want with our son?" Jack demanded.

"Come on, I can't celebrate Danny's special day with my own family?" Dark Danny asked. "It's my special day too."

"Mom, dad, meet...well, me," Danny said.

"I'm your son from an alternate timeline," Dark Danny explained.

"But you were locked up by Clockwork," Sam said. "How did you get free?"

Dark Danny shrugged. "He let me go," he responded.

"What? No, he couldn't have," Danny said, shaking his head. "But that doesn't matter. What are you doing here?"

"I'm here to lay waste to the foolish ghost boy who spoiled my plans all those years ago," Dark Danny said emotionlessly.

"Ah, come on...can't we...you know...uh...bygones?" Danny asked awkwardly. Dark Danny responded by waving his hand and a faint green aura surrounded everyone except Danny and Dani, rendering them immobile.

"Danny, do something!" Jazz exclaimed.

Dani immediately transformed into her ghost form and rose to meet Danny and Dark Danny. Dark Danny noticed this and remarked, "Another halfa, huh. No matter, you're both no match for me." Danny sent a ray of ecto-energy in Dark Danny's direction but Dark Danny quickly deflected it and sent one of his own in return. Danny quickly dodged the blast and it passed through the ceiling. He then quickly flew toward Dan and knocked him backward and out of Fenton Works. This freed his family from Dark Danny's ecto-hold on them.

Dark Danny stood up. "You're quicker," he observed.

"That's not all that's new," Danny said. "As a deputized officer of the local police department, I command you to freeze!" He sent a pair of ice beams Dark Danny's way. These were quickly deflected with an ecto-shield and redirected back at Danny. Danny was able to dodge the first beam but the second beam blasted him to the ground. Jack and Maddie had joined the fight by this time and they teamed up with Dani to create a huge beam of ecto-energy. Dark Danny simply rolled his eyes and reshaped his body. The large ecto-ray passed harmlessly through a hole he had created in his stomach.

Danny got back up and stepped defensively between his family and Dark Danny. After warning his family to get back he let out a ghostly wail. Dark Danny responded with one of his own. The windows of several nearby buildings shattered and the earth shook with the raw power of the battle taking place. The two ghost fighters circled each other, not letting up. Danny soon found himself running out of breath. Though it was his most powerful move, it was a very draining move and could only last so long. Eventually Dark Danny was able to overpower Danny. The force of the wail sent Danny flying and forced him back into his human form.

"Come on, Danny, you can do better than that," Dark Danny taunted. "Oh, that's right, you can't! You got lucky the first time, but your luck has run out."

Danny ignored Dark Danny and transformed back into his ghost form. He created several clones of himself and mustered all the strength he could. All of his clones let out the ghostly wail. Dark Danny again returned the move but was not able to deflect all of the clones. He grunted in pain and fell to the ground. Danny took this opportunity to rush at Dark Danny and punch him in the jaw. Caught off guard by the power and speed being displayed by Danny, Dark Danny did not dodge the blow in time. Danny's green eyes glowed brighter than they usually did, Dark Danny observed. He meant business.

Dark Danny chuckled. "You're tougher than I thought."

"I've been eating my vegetables," Danny quipped. "Stay away from my family."

"Oh Daniel!" Kairos called. He flew up to the scene of the battle. "There you are. Why are you wasting your time with this ghost child? We have work to do!"

Dark Danny glared at Kairos. "I told you I had to take care of something first. This 'ghost child' would just get in the way of things."

"Wait...who is this guy?" Danny asked, confused.

Kairos grinned. "Why don't I help you?"

Dark Danny put on his time medallion. "Do it."

"Wait, a time medallion? So Clockwork _is_ behind this!" Danny exclaimed.

"No, _I'm_ behind this," Kairos said, laughing. "I am Kairos, manipulator of time and Clockwork's younger brother. Speaking of which...time out." Before Danny could say anything else, Kairos pressed a button on his time staff and everyone was frozen by Kairos's power.

Dark Danny moved forward, his hands glowing with red ecto-energy. He had been waiting for this moment for years. It was time to get revenge.

Before he could do anything, however, a clock symbol appeared around each person and they were all transported to Clockwork's lair. Kairos snapped his fingers and time returned to normal.

"They're gone," Kairos said. "Now let us do what must be done."

"Very well," Dark Danny said. "But don't let your guard down. As long as that younger version of me is still alive, we could have a problem."

"He will not be a problem the next time we see him," Kairos assured. "Now come along. Chop chop." Dark Danny glared at Kairos, resentful that he was being treated as a servant, but he obeyed. For now.


End file.
